The invention relates to a method of spectral or colorimetric characterisation of a self-illuminating imaging system, in which the imaging system produces a color field which is matched visually with a reference color field.
Self-illuminating imaging systems should be understood to include in particular computer monitors, televisions, large image projectors and the like. Spectral or colorimetric characterisation denotes the spectral or colorimetric description of the current imaging properties of an imaging system which for example can also consist of a combination of the actual monitor with driver software and/or graphics card.
Nowadays for characterisation of color monitors special colorimeters are usually used which are equipped either with filters adapted to the sensitivity of the eye (frequently designated as three-area or tristimulus colorimeters) or spectral sensors (in spectral photometers). So-called color profiles are then produced with the aid of the measurement data.
However, the known colorimeters have the disadvantage that the illumination conditions of the monitor environment are not taken into account in the encased colorimeter. Also, in the less expensive measuring devices the measurement geometry does not correspond approximately to the spherical shape of the human eye.
A relatively economical and simple method is represented by visual matching with color sample fields, in which the color sample fields are held alongside the imaging system to be examined in order that a color field produced on the imaging system can then be appropriately matched. However, this known method only constitutes an approximate solution, since for good matching a sufficient illumination of the color sample field on the one hand and the least possible incidence of light onto the monitor on the other hand would be necessary, which however cannot be achieved because the color sample fields must be kept in the immediate proximity of the monitor and of the color field produced thereby.
Furthermore, metameric effects are produced due to the variable illumination of the color sample field and self-illuminating imaging system.